Useful enterobacteria are liable to acid, water or heat, and when they are directly incorporated in the body without any protective means, almost all of them are killed. However, by protecting the useful enterobacteria from acid, water or heat with an enteric capsule, a surviving rate thereof can be increased.
For example, such a capsule containing the useful enterobacteria is disclosed in Japanese Laid-Open Patent Publication No. 61-151127. In Japanese Laid-Open Patent Publication No. 61-151127, there is described a method for producing an enteric capsule comprising: mixing bacteria cells with vehicles such as starch; dispersing the resulting mixture in a hardening oil; encapsulating the resulting dispersion with an enteric coating consisting of gelatin and pectin; and then dipping the resulting capsule in an aqueous calcium chloride solution to impart acid resistance to the capsule. In the capsule obtained by this method, intrusion of water into a content dispersed in the hardening oil can be interfered temporarily by the hardening oil, however, bad influence with time caused by residual water which is contained in a coating of the capsule and the hardening oil can not be avoided. In addition, in order to impart acid resistance to a coating of the capsule consisting of gelatin/pectin, the capsule must be dipped in an aqueous calcium chloride solution. At this step, water is liable to transfer to a content through a coating of the capsule, as well as heat resistance of the resulting capsule is poor.
On the other hand, in Japanese Laid-Open Patent Publication No. 62-263128, there is described a capsule wherein the useful enterobacteria are isolated from a coating of the capsule via a hydrophobic substance which is non-flowable at ambient temperature. In this structure, penetration of water into the content can also be interfered temporarily, however, bad influence with time caused by residual water which is contained in a coating of the capsule, the hardening oil and other substance, can not be avoided, as well as heat resistance of the resulting capsule is poor.